The treatment of bank filtrate by hybrid flocculation/ultrafiltration was investigated. Aeration during filtration did not have an effect on membrane performance as expressed as the rate of permeability. However, aeration in the membrane container resulted in a release of organics which increased dissolved organic carbon (DOC) in the filtrate. For non-aerated raw water adsorption of dichloroethene (DCE) was improved by the flocculation/ultrafiltration-process considerably, as shown in isotherms and breakthrough curves. Includes 8 references, table, figures.